Only 25 and nothing more? which player? Not enough info.
I'll give you basic - this will work for any players and will happen every 25 units killed (all kind of units). You need to create variable, click on button look like yellow X in trigger screen. Then add new variable by clicking green "+X" button, give it a name lets say "unitkilled" and variable type is "Interger."
Then with trigger.
Events
Unit - A unit Dies
Conditions
Actions
If (All Conditions are True) then do (Then Actions) else do (Else Actions)
If - Conditions
unitkilled Less than 25
Then - Actions
Set unitkilled = (unitkilled + 1)
Else - Actions
Set unitkilled = 0
Unit - Create 1 ...
i would do it quite like that, but with a small modification:
event: - a unit dies cond: act: - set Kills[PlayerNumber(OwningPlayer(KillingUnit))] = Kills[...] + 1 - if - - Kills[...] % 25 = 0 (% means modulo) - then - - <do the reward>
modulo is a math operator that returns the rest of a division through a number. e.g. 3%2 = 1 5%2 = 1 4%2 = 0 16%7 = 2 ...
using a module has the advantage of beeing able to grant another reward every larger anount of kills (simply add another if with an Kills[]%#...)
and by using an array you have the advantage of having the kills stored for all players in only one variable, keeping your code clean ^^
the only disadvantage on the code, as it is above is, that it also works for all the neutral players (simply add cond: Playernumber(Owner(KillingUnit)) <= 12 - there are only 12 human-player slots)
i hope this helps you ^^ (and no offence to haloboycs - your code is fine, even though it works only for one player ^^)